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Newe Weir, River Don

Weir Removal Technical Assessment

May ��

Newe Weir, River Don

Weir Removal Technical Assessment

Client: River Don District Salmon Fishery Board

Document number: ��

Project number: �!"�#

Status: Client Issue

Author: David Warren & Stephanie Davidson

Reviewer: Kenneth MacDougall

Date of issue: .� May �#.�

Filename: .�#�.� Newe Weir Technical Assessment Report.docx

Glasgow Aberdeen Inverness Edinburgh

Craighall Business Park

! Eagle Street

Glasgow

G" 6XA

#.". ". �#"#

[email protected]

www.envirocentre.co.uk

Banchory Business

Centre

Burn O’Bennie Road

Banchory

AB . �ZU

#. # !�� 6�

Alder House

Cradlehall Business Park

Inverness

IV� �GH

#."� �6" �.�

Suite .."

Gyleview House

Redheughs Rigg

Edinburgh

EH.� 6DQ

#. . �.� 6� #

This report has been prepared by EnviroCentre Limited with all reasonable skill and care, within the terms of

the Contract with River Don District Salmon Fishery Board (“the Client”). The report is confidential to the Client,

and EnviroCentre Limited accepts no responsibility of whatever nature to third parties to whom this report may

be made known.

No part of this document may be reproduced or altered without the prior written approval of EnviroCentre

Limited.

River Don District Salmon Fishery Board May

Newe Weir, River Don; Weir Removal Technical Assessment

i

Contents Introduction .....................................................................................................................................................

. Project Background .................................................................................................................................

. Scope of Report ....................................................................................................................................... Baseline Conditions .........................................................................................................................................

. Site Location ............................................................................................................................................

. Baseline Surveys ......................................................................................................................................

. Newe Weir ..............................................................................................................................................

. Removal Options Considered .................................................................................................................. Hydrological Assessment and Hydraulic Modelling .........................................................................................

. Hydrological Assessment ........................................................................................................................

. River Don .................................................................................................................................................

. Hydraulic Model Build .............................................................................................................................

. Model Results .......................................................................................................................................... Hydromorphological Assessment ..................................................................................................................

. Site Description and Baseline Conditions ..............................................................................................

. River Don Channel Characteristics in the Vicinity of Newe Weir ..........................................................

. Potential Geomorphological Implications of Newe Weir Removal .......................................................

. Specific Impacts .....................................................................................................................................

. Possible Mitigation Measures ............................................................................................................... Weir Removal Options Appraisal ...................................................................................................................

. Removal Options ...................................................................................................................................

. Partial Removal .....................................................................................................................................

. Full removal ...........................................................................................................................................

. Newe Hydro Scheme ............................................................................................................................. Summary ........................................................................................................................................................

References .............................................................................................................................................................

Appendices A Annual exceedance probability (AEP) and return periods conversion table B Hydrological Analysis C Site Photographs D Hydraulic Modelling Results E Sediment Regime Calculations F Topographical Survey

Figures Figure . ‐ Site location plan and hydrological study extents (red line) ................................................................ Figure . ‐ Features along the study reach ............................................................................................................ Figure . ‐ Location map for the study reach of the River Don ........................................................................... Figure . ‐ Newe Weir ......................................................................................................................................... Figure . ‐ River Don immediately upstream from Newe Weir ........................................................................... Figure . ‐ Wolman pebble counts from representative riffles and bars up‐ and down‐stream of Newe Weir . Figure . ‐ Confluence of Newe hydro scheme lade, Burn of Deochry and River Don at the A bridge ......... Figure . – Bed sediment immediately upstream of weir for removal options .................................................. Figure . ‐ River long section upstream of existing weir (not to scale, and with vertical exaggeration) ............ Figure . ‐ Revised hydro intake locations .......................................................................................................... Figure . ‐ Relocated hydro intake location plan ................................................................................................



ii

Tables Table . ‐ Estimated peak flows ............................................................................................................................ Table . ‐ Evaluated scenarios ............................................................................................................................... Table . ‐ Morphological description of the River Don .......................................................................................

River Don District Salmon Fishery Board May �#.�


.

1 INTRODUCTION

�.� Project Background

EnviroCentre has been commissioned by the River Don District Salmon Fishery Board to undertake a technical

assessment of the options for the removal of the Newe Weir on the River Don, near Strathdon.

The River Don District Salmon Fishery Board (RDDSFB) want to remove the Newe Weir on the River Don. The

weir presently has a fish pass, but remains an obstacle to migratory fish passage. The weir is presently used by

a third party to abstract river flows that pass through the adjacent Newe Hydro Scheme before being

discharged back to the main channel downstream. The removal of the weir is intended to improve fish passage,

restore river continuity, reinstate natural river processes upstream, reduce maintenance requirements and

improve flood risk.

�.� Scope of Report

This report details the outputs from the below scope of works:

• Baseline surveys: topographic, hydrographic and hydromorphology;

• Hydrological assessment and hydraulic modelling;

• Hydromorphological assessment;

• Weir removal options appraisal, including impact assessment and outline mitigation options.

This assessment does not cover wider ecological aspects of the weir and removal options.



�

2 BASELINE CONDITIONS

�.� Site Location

The Newe Weir is located on the River Don, approximately �km east of Strathdon, Aberdeenshire, at National

Grid Reference (NGR) NJ �# .�#�. A Location plan is presented as Figure �...

Figure �.� - Site location plan and hydrological study extents (red line)

The land surrounding the weir is predominantly agricultural land, with an area of dense forestry on the

northern banks. A small hydro-electric power station is located to the northeast of the weir, adjacent to Newe

Lodge and the Bridge of Newe. A more detailed description of the River Don at this location is provided in

Section .�. The length of the study reach is approximately km, extending ..�km upstream and ..�km

downstream from the weir.

�.� Baseline Surveys

A number of baseline surveys have been undertaken to assess the current conditions within the river at the

location of the weir, as well as upstream and downstream of the structure.

A topographical survey was undertaken which detailed cross sections of the river channel, structure details and

bank heights along the study reach, providing details for input into the hydraulic model of the river, as well as

crest and bed levels at the weir location itself.

A hydrological survey has been undertaken to determine the flow conditions within the channel, which

involved a walkover survey of the full study reach. This identified any dominant flow regimes, locations of



significant structures and features within the river channel, as well as gathering information regarding bank

conditions, floodplain levels and likely overland flow routes. This walkover study was undertaken at the same

time as a hydromorphological survey of the river.

This hydromorphological survey inspected the nature and stability of the river channel along the study reach

along with the general river conditions, natural fluvial processes and potential sediment transport regimes up

and downstream of the weir. This involved Wolman Pebble Counts at riffles and bars both up and downstream

of the weir structure.

The surveys have formed the basis of the weir removal assessment in the following sections.

In this report, where left and right banks are used, these refer to looking downstream.

�.7 Newe Weir

The Newe Weir spans the main channel of the River Don. A weir was initially constructed at Newe sometime

between .!�� and .6## as it does not appear on the first edition Ordnance Survey (OS) map of .!�� (NLS,

n.d.), but is shown in the second edition of .6##. This original weir provided an offtake to supply water via a

lade to a sawmill on the southern (right) bank of the river. The weir was subsequently upgraded to provide an

offtake to the northern bank (left) to power a hydro scheme prior to the national power grid reaching this area.

The original hydro power scheme has long ceased to exist, however a more recent intake has been formed

immediately upstream of the weir to supply water to an Archimedes screw hydro turbine which was installed

approximately .# years ago.

The weir is constructed from stone and concrete, having bankside walls of similar construction immediately

upstream, while a former concrete abstraction lade and large stone boulders are present immediately

downstream of the weir.

A topographic survey of the weir and surrounds has been undertaken (Appendix F), which identifies that the

typical hydraulic head across the weir is ..! m, with upstream water depths of typically #. m – #.� m, although

locally deeper, and downstream water depths of typically ..� m, but deeper than this around the toe of the

weir.

The weir contains a pool and weir type fish pass within the central section of the weir. This has been in place

for many years and has been subject to modifications to improve the flow conditions within the fish pass over

the years. The weir is not considered to be a barrier to fish migration, but will remain an obstacle at certain

flows.

�.8 Removal Options Considered

Two removal options are considered in this assessment:

Partial removal: Assumes that the weir crest is lowered by . m. This will leave a typical drop of

approximately #.! m across the weir footprint.

Full removal: Assumes that the weir crest is lowered by � m.



"

3 HYDROLOGICAL ASSESSMENT AND HYDRAULIC MODELLING

7.� Hydrological Assessment

The River Don is a major Scottish river which rises in the Cairngorm Mountains and routes east to outfall into

the North Sea at Aberdeen. There are a number of river gauges located along the length of the river, including

at the location of the Newe Weir (..##� Don @ Mill of Newe). This gauge has records from .6!6 through to

.66", however the gauging station was not rated for high flows.

In this report the likelihood of a flood event with a certain magnitude is quantified using the concept of Annual

Exceedance Probability (AEP) expressed as a percentage. The other method that is often used to express flood

risk is the concept of ‘return period’. The relationship between AEP and ‘return period’ is documented in

Appendix A.

The hydrological study undertaken for this assessment focussed upon the peak #.�% AEP flows (equivalent to .

in �## year return period) in order to determine the existing and proposed flood risk in the most extreme

scenarios, and so peak flow estimation was undertaken using two methods for estimating flows in ungauged

catchments, the Revitalised Rainfall-Runoff Method, version � (ReFH�) and the FEH Statistical Method.

Catchment descriptors were derived for the catchment using the FEH Web Service (CEH, �#.�) and are

provided in Appendix B. The catchment area at the location of the weir was estimated to be approximately

.6�. km�. The results of the hydrological analysis are presented in Table .., showing the peak flows for the

�#%, % and #.�% AEP flood conditions. Further details of the calculations are presented in Appendix B.

Table 7.� - Estimated peak flows

AEP% Peak Flow Rate (m7/s)

ReFH� FEH Statistical Method

�# �#. ��.�

.�#.! ."�..

#.� �...� ��#.�

The ReFH� method produces higher flow figures for the lower return period events, however the Statistical

Method produced a higher flow estimate for the #.�% AEP event. In order to be conservative the Statistical

method peak flow of ��#.�m /s was adopted. It is also considered that the Statistical Method is most suited for

estimating flows in catchments of this size.

7.� River Don

The River Don through the study reach meanders through a wide valley floor, with extensive floodplains on

both north and south banks. The site walkover for the hydrological and hydromorphological surveys was

undertaken on ��th

November �#.�, and a photographic record of the walkover is presented in Appendix C. A

detailed description of the river is provided in Table ".., however the below description focuses on key

features along the reach pertinent to the hydraulic modelling and assessment. These locations are presented

on Figure ...

At the upstream end of the reach a small footbridge crosses the river which clearly spans the channel and does

not present a significant restriction to flows. The river appears stable with a width of approximately �#m, and

banks of approximately equal heights. Downstream of the footbridge the river turns to the left (east), and the



�

outside of the river channel has been protected with rock armour, approximately �m high, adjacent to the

small road running parallel to the south.

Figure 7.� - Features along the study reach

As the channel routes further south, the banks on the right hand side rise considerably, being approximately -

.�m higher than the left, and so the natural floodplain is located to the north of the river, across the

agricultural fields.

Approximately .#-.�m upstream of the weir crest the intake for the hydro power plant is located on the left

hand bank. This consists of a small lateral weir, covered with a metal trash screen, and flows from this intake

are routed by pipe approximately ��#m to the east to the hydro power plant. This consists of an Archimedes

Screw which is rotated by the flow and head of water passing through the plant. The outfall channel from the

hydro plant routes to the east and converges with the River Don immediately upstream of the Bridge of Newe.

The Newe Weir itself has a width of approximately � m at its crest, and the drop in height through the

structure is approximately �.�- m. The natural channel with through this section of the river is approximately

�#-��m. The Weir is constructed from concrete and a fish ladder is located in the centre of the weir structure.

On the northern side of the weir, the historical intake for the hydro scheme is located, however this is no

longer in use and is sitting redundant. A concrete wall is also located along the right bank at the location of the

weir.

During the site walkover it was noted that there were stockpiles of gravel adjacent to the channel upstream of

the weir. It was later established from the client that gravel and sediment is removed annually from behind the

weir. It was noted that the depth of the channel was greater adjacent to the hydro intake where it appeared

more gravel had been removed.



�

The bed level for approximately �#-�#m upstream of the weir was shallow with a depth of approximately #.� m

measured from the topographical survey. This is due to the build-up of sediment trapped behind the weir and

prevented from being transported downstream.

Downstream of the weir the channel returns to a less artificially constrained state with bedrock appearing

along the banks. A small pool is located at the toe of the weir which is wider than the downstream channel

width, at approximately ��- #m. The river channel as it continues to route east is approximately .!-�#m wide.

The river turns to the left (northeast) adjacent to the properties located on Waterside Road, and at this

location there is significant bank protection on the right banks in the form of large boulders. This can be seen in

photograph ! in Appendix C.

Approximately .##m further downstream, the outfall from the hydro power plant discharges into the main

river channel on the left bank. This outfall channel is approximately �m wide, and on the day of the walkover

survey the flow within this channel was very similar to the flow in the River Don. Immediately downstream of

this outfall channel a small tributary (Burn of Deochry) discharges into main river channel, also on the left bank.

This location is illustrated in photograph .. in Appendix C.

The River Don continues in a north-easterly direction, passing below the Bridge of Newe, before then routing in

an easterly direction, meandering through agricultural fields. The channel through this downstream section of

the study reach is approximately .�-.�m wide.

7.7 Hydraulic Model Build

7.7.� Model Elements

A .-Dimensional (.D) hydraulic model constructed in Infoworks RS (version ...�) based upon the surveyed river

sections.

The model contained � surveyed sections, � bridges and the weir structure. A number of interpolated sections

were also added to the model to increase model run stability. Bank levels were taken from the topographical

survey, and where river sections were extended across the floodplain, OS Terrain � DTM information was used

to supplement the topographical survey.

7.7.� Manning’s Roughness

The Manning’s ‘n’ roughness vales used within the model were based upon observations of the channel, bank

and floodplain conditions during the site walkover. The values have been based upon the values stated by

Chow (Chow, .6�6), and range from #.# �-#.#"� for the channel bed, and #.#"#-#...# for the banks and

floodplains.

7.7.7 Model Scenarios

In order to determine the baseline conditions for the peak #.�% AEP event the model, and then assess the

impact of any removal works, the hydraulic model was run for a range of scenarios which are listed in Table .�

below.



�

Table 7.� - Evaluated scenarios

Scenario Description

A. Functional Floodplain* Baseline Scenario.

Flood levels under typical / as surveyed conditions during a 0.5% AEP

river flow.

B. Partial Removal of Weir Weir level reduced by #.6-.m. Bed level in upstream channel lowered

to accommodate lowered weir crest. Lowering extends approximately

�#-!#m upstream. Some infilling of the pool downstream of weir.

C. Full Removal of Weir Bed level at weir lowered by �m. Bed levels upstream lowered to

accommodate change in levels. Downstream pool also filled in with

sediment from upstream. Upstream sediment removal/bed re-grading

extends approximately �#m.

*as defined by Scottish Planning Policy (SPP).

7.8 Model Results

7.8.� Assessment of Baseline Flood Risk – Scenario A

SEPA’s Online Flood Maps indicate that during the #.�% AEP event there would be significant flooding in the

surrounding area, with flows out of bank extending across the majority of the floodplain. Upstream of the weir

flows are shown to be out of the northern banks covering the fields between the river and the A6"". Adjacent

to the weir structure flows are shown out of bank on both the north and south of the river with extensive

flooding surrounding the hydro power plant. Further downstream, the SEPA Flood Maps show that the

properties to the south of the river on Waterside Road would be inundated with flows routing out of the right

banks.

The Baseline Scenario A was run to more accurately determine the flood extents in this area and to verify the

flood risk to any properties in the locality.

From the model runs it was determined that as per the SEPA flood map, there was significant out of bank

flooding in the upper area of the study reach, predominantly from the left bank at the location just

downstream of the small footbridge. This would route flood waters across the large floodplain to the north of

the river, inundating the agricultural fields through this area. Along the central part of the river reach upstream

of the weir, there are additional out of bank flows noted on the left banks which would also inundate the

northern floodplain. Flood flows on the floodplain would route in an easterly direction. A small amount of

flooding is predicted out of the right (southern) banks along the river upstream of the weir.

At the location of the weir, flows are shown to route out of bank on both sides during the peak of the flood

event. On the left banks, the flood flows would route east towards the hydro power plant, and on the right

banks the water would overtop onto agricultural fields. Immediately downstream of the weir, flows would

continue to be out of both banks, with the left inundating the dense forestry area, and the right extending

across the floodplain towards Waterside Road.

At the houses located on Waterside Road downstream of the weir, the ground levels have been taken from the

OS Terrain � DTM and are estimated to be approximately ��.�-�� mAOD. At cross-section DON_.�..

adjacent to this location, the peak water level is estimated to be approximately ��..6 mAOD. As such it is

considered that in the baseline scenario these houses would be at risk of inundation during the #.�% AEP

event.

Downstream of the Bridge of Newe, flows are indicated to spill out of the right bank and route across the

floodplain to the south of the river.



!

Detailed results of the maximum water levels at each cross section are presented in Appendix D.

Based upon the results of the modelling of the baseline Scenario A, it is considered that the flooding shown on

the SEPA Online Flood Maps would be representative of the #.�% AEP event.

7.8.� Scenario B - Partial Removal

The baseline model was revised to include a partial removal of the weir structure, which included reducing the

height of the crest by #.6-.m across its full width, as well as lowering the bed levels upstream to account for

this lowering. The pool at the downstream toe of the structure was also partially backfilled to allow a smoother

transition through the structure.

The results of the modelling identified that in the upstream of the study reach the peak water levels and

estimated out of bank spills were broadly similar to the baseline scenario, which was as to be expected.

Immediately upstream of the weir structure where the bed levels had been reduced, the peak water level had

dropped in line with the drop in bed level, and this had a backwater affect which extended approximately

�#m upstream.

Immediately downstream of the reduced height weir where the pool was partially backfilled, the peak water

level was estimated to increase which was in line with the increase in bed level. The three river cross sections

downstream of this all showed in increase in peak water levels, but only by a maximum of �mm. Out of bank

flows on the left bank through this section were also shown to marginally increase which would route through

the wooded area and east towards the hydro power plant. Flows out of the right bank were shown to be at

approximately the same level.

The peak water levels and bank overtopping adjacent to the properties on Waterside Road were estimated to

be only !mm lower than the baseline scenario, indicating that the partial removal of the weir structure would

have minimal impact upon the flood risk to these properties.

In the downstream section of the study reach the peak water levels were shown to be between �#-"#mm

different, however the magnitude of these would not be considered to be significant due to the extents of the

wide floodplains through this area.

It is considered that the partial removal of the weir structure and lowering of the crest would have minimal

impact upon the flood risk to properties and land both up and downstream of the weir structure.

7.8.7 Scenario C – Full Removal

The baseline model was revised to include the full removal of the Newe Weir structure, which included the

removal of the concrete structure and the regrading of the channel bed up and downstream. The removal of

sediment and gravel from upstream of weir was assumed to extend for approximately �#m, with the

downstream pool also being backfilled so as to provide a smoother transition through the level change. It is

anticipated that the concrete sides to the weir structure would be retained following the removal of the weir to

provided support to the banks through this location and so these were retained within the model.

The modelling has indicated that as in the partial removal scenario, the upstream section of the study reach

would not be affected by the weir removal. The peak water levels and bank overtopping rates are as per the

baseline scenario, indicating no extensive upstream impact from the weir removal.

Where the bed levels within the channel have been lowered, the peak water level was estimated to also be

lower, with a maximum decrease at the weir of approximately ..!m. Out of bank floodplain flows across the

northern floodplain upstream of the weir structure location were also indicated to increase. This is considered



6

to be due to the lowered bed levels at the location of the removed weir allowing greater floodplain flows back

into the river channel, and thus providing a less restricted flow route across the floodplain.

Downstream of the removed weir, the peak water levels were estimated to increase marginally, however the

maximum increase was only indicated to be !mm. At the location of the properties on Waterside Road the

peak water level was estimated to be �mm lower than the baseline scenario, and so it is considered that there

would be negligible impact upon the flood risk to these properties.

In the downstream portion of the study reach the water levels differ from the baseline scenario by a maximum

of approximately �#mm, however as noted above this is not considered to have any detrimental impact upon

any downstream properties.

Following review and comparison of the peak water level results for the #.�% AEP event, it is considered that

the full removal of the weir structure would have a negligible effect on any upstream or downstream

properties in terms of flood risk. Out of bank flows were indicated to increase into the northern floodplain

upstream of the structure, however these would route east across agricultural land and then back into the

main river channel further downstream.



.#

4 HYDROMORPHOLOGICAL ASSESSMENT

8.� Site Description and Baseline Conditions

A reach of River Don between The Colquhonnie House hotel and the A6""/A6� road junction was inspected on

the ��th

of November �#.�; this included the Newe hydro scheme lade. The water level at the gauging station

at Culfork was #.��m, which is slightly higher than the average recorded flow level of #..�m. The weather was

dry and very frosty on the day of survey.

The extent, nature and stability of the channel along a �.!km reach was inspected, along with the general river

conditions in the immediate area of influence, with particular reference to the Newe Weir and hydro scheme.

A location map is provided in Figure "...

A morphological summary of the river conditions at and around the site is provided in Table "...

Figure 8.� - Location map for the study reach of the River Don

Table 8.� - Morphological description of the River Don

Geomorphological feature Description

Valley and terrain

Upland catchment dominated by fluvio-glacial

surficial deposits and metamorphic basement.

Managed agricultural land and temperate forest

are the predominant land uses. The valley is

largely symmetrical with heights greater than

"##m. The valley sides are stable, composed of

glacio-fluvial loose debris and well-vegetated. No

signs of failure are apparent along the river in the

terraces. The valley floor is continuous and

greater than .# channel widths in places. The

riparian buffer strip is wide and continuous.

Study reach

Newe weir and

hydro scheme



..


Floodplain

The valley is confined within at least one

continuous terrace. The valley floor is continuous

forming a wide floodplain when not confined by

terraces. Fluvio-glacial deposits dominate the

surface geology and managed land use.

Vegetation comprises improved grassland,

deciduous woodland and coniferous forest.

Channel planform

No recent overbank deposits were noted however

trash lines were noted approximately .m above

the bankfull level. The planform is sinuous with

regular meanders and local bank erosion causing

minor lateral activity. Meander scars are apparent

on the floodplain as topographic lows marked by

a change in vegetation.

Channel

The bankfull width and depth on the day of survey

varied from approximately .�m in pool sections

to .#m in riffles, and between .m and #. m

respectively. The average reach slope is

“moderate” (�-!°) with a number of gravel point

bars and lateral bars. The flow type is

uniform/rapid, or plane-riffle, with pool-riffle

features. Artificial levees are noted along the

length of the surveyed section upstream of the

A6"" road bridge. Levee heights vary between .m

and m above the channel bed.

Bed sediment

The bed substrate ranges from cobble to gravel

clasts with occasional boulders. The bed armour is

mobile. Barforms are commonly point bars with

riffle features. Both bed and bar clasts are well

imbricated.



.�


Left bank characteristics

The bank is layered, comprising a coarse sand and

gravel matrix capped by thin sandy soils. A layer

of cobbles and gravels is apparent at the bank toe

of variable thickness. Bank top vegetation

comprises healthy grass, sedges, and shrubs with

occasional small deciduous trees. Mature

vegetation cover is sparse and discontinuous over

the upper bank forming a narrow belt adjacent to

the channel. Local bank erosion was noted on the

outside of meander bends or opposite bars. River

flow processes are parallel to the bank.

Geotechnical failures are apparent on the

unstable bank faces in the form of slab failures.

Right bank characteristics

The natural bank materials and processes are

similar to those described for the left bank.

However, the right bank has been heavily

armoured by boulders at a number of locations,

most notably at the outside of meander bends

and adjacent to the residential properties at

Waterside.

Interpretative observations

The River Don river valley generally has

insignificant stability problems with the stable

channel being well-adjusted to the existing

hydrophysiological regimes under the current

climate. The stable bed and banks indicate a

steady state sediment balance with the river

establishing dynamic equilibrium under the

existing conditions.



.

8.� River Don Channel Characteristics in the Vicinity of Newe Weir

The Newe Weir presents an obstacle to fish migration (Figure ".� and Figure ". ). Anecdotal evidence suggests

that adult fish are able to migrate to the pool at the base of the weir but find the existing fish pass difficult to

navigate. On the day of survey, high velocity turbulent flows were observed within the fish ladder.

A spoil heap of gravel and cobbles was observed adjacent to the weir at the left bank and a deep scour hole

was noted in the River Don channel at the hydro scheme intake. These observations support the anecdotal

evidence that the River Don main stem is dredged upstream from the weir to keep the hydro scheme intake

clear of sediment.

Figure 8.� - Newe Weir

Figure 8.7 - River Don immediately upstream from Newe Weir

The River Don has aggraded upstream from Newe Weir such that there is currently a signigicant drop-height in

bed levels between upstream and downstream of the weir. Observations indicate that the aggraded clasts are

predominantly gravel-size and finer. Representative Wolman pebble counts from an upstream riffle and bar

show a marginally finer sediment distribution than samples obtained from a downstream bar and riffle (Figure

"."). These results and observations suggest that the weir is currently trapping finer-grained sediment

potentially leading to a depletion in fines downstream between the weir and the tributary at the A6"" road

bridge.

The Burn of Deochry tributary at the downstream road bridge has formed a junction bar of sand- to gravel-size

clasts at the confluence with the River Don (Figure ".�). A large super-elevated point bar adjacent to the



."

properties at Waterside appears to represent deposition from higher flow regimes than the normal range of

flows, and is thus, relict. This may be partly induced by the excessive artificial bank armouring on the opposite

right bank and therefore inhibits the natural flow process and sediment dynamics.

High flow velocities were noted in the Newe hydro scheme lade on the day of survey. Similar to the Burn of

Deochry tributary, the hydro scheme lade appears to be supplying the River Don main stem with finer-grained

sediment at the confluence suggesting this size-range is syphoned into the lade at the upstream intake.

Upstream riffle, DB� = D�mm. Upstream bar, DB� = EBmm, Dmax = �B�mm

Downstream riffle, DB� = DBmm Downstream bar, DB� = EBmm, Dmax = ��mm

Figure 8.8 - Wolman pebble counts from representative riffles and bars up- and down-stream of Newe Weir

Figure 8.B - Confluence of Newe hydro scheme lade, Burn of Deochry and River Don at the AF88 bridge



.�

8.7 Potential Geomorphological Implications of Newe Weir Removal

Transport of sediment through a catchment and along the length of a river is continuous. Increased erosion in

the upper reaches of a system can affect a considerable length of the downstream river environment for many

miles (and for many years or decades) as the increased sediment loads propagate downstream. Along the river

channel transport system itself, channel forms (such as bars) may appear to be stable but their composition is

in fact changed on an annual or biannual basis as their grains are replaced. Similarly the sediments that make

up the river floodplain (valley floor and terraces) are typically mobile on a time scale of decades or centuries.

The floodplain acts as a storage reservoir for sediments transported in the channel, alternately storing

sediment by deposition and releasing sediment to the channel by bank erosion. The integral connection

between floodplain and channel is crucial in maintaining the dynamic nature of a fluvial system.

A number of indicators have been identified as resulting from disruption of the longitudinal continuity of the

river system and interruption of the sediment transport regime (Kondolf, .66�). Instream mining, for instance,

directly alters the channel geometry and bed elevation and produces a local sediment deficit.

Weirs trap some of the incoming bedload sediment, passing “hungry” water downstream which typically

erodes the channel bed and banks to regain part of its sediment load. The direct results of incision include

undermining of structures, such as bridge piers, and exposure of buried pipeline crossings. Incision of the

riverbed typically causes the alluvial aquifer to drain to a lower level resulting in a loss of aquifer storage. Just

as below dams, gravel-bed rivers may become coarsened or armoured. The increase in sediment size can

threaten the success of spawning by salmonids.

Although the River Don does not show adverse signs of sediment starvation downstream from the Newe Weir,

the downstream surveyed reach does not show the same diversity in bed and bar forms as the upstream reach.

It is anticipated that removing the Newe Weir would re-introduce the full range of bedload and suspended load

sediment sizes to the downstream reaches of the River Don; this would encourage the channel to distribute the

additional supplied sediment over a range of flows to re-establish dynamic equilibrium. As a result of the

proposed weir removal a more varied channel morphology would develop to the advantage of in-channel

biota.

The weir removal process should provide mitigation against the adverse effects of the steep height difference

between the channel bed above and below the weir. The weir removal will alter the equilibrium profile of the

bed, creating a locally steeper gradient. If mitigation is not included as part of the weir removal process, there

is the potential for headcutting to occur as an over-steepened knickpoint can erode upstream.

8.8 Specific Impacts

8.8.� Shorter term impacts

In the full weir removal scenario where the bulk of the sediment is removed from the upstream channel behind

the weir, the short term impact may be that there may be a decrease in sediment supply during high flows

when stored sediment will no longer be available to be transported across the weir to downstream. The

downstream bar and bedforms may become “fixed” in that they will no longer evolve or change over the

medium-to long-term.

Alternatively, if not all of the upstream sediment is removed during the removal of the weir, there will be a

quantity of sediment which is likely to be transported downstream immediately following weir removal. It is

likely that high flows will transport this sediment downstream and that it will naturally infill the downstream

pool with the coarser material, whilst the finer material will be transported as suspended load further



.�

downstream. This will alter the river’s sediment regime locally in the short-term; however, over longer

timescales it is considered that a new sediment transport equilibrium will be established.

8.8.� Longer term impacts

Based upon the width of the river, the length upstream that sediment may be removed from and an estimate

of the average depth of sediment removal, it is estimated that up to approximately ",###m may require to be

excavated from the river channel. If the weir is just removed with no thought to grading the bed levels then it is

suggested this could have significant consequences downstream. All of the sediment could be moved in the

next couple of spates and dumped overbank, block the tributary and lade confluences, and start forming mid-

channel bars.

Permanent removal of the full volume of sediment from behind the weir has the potential to deplete the

sediment supply for the downstream reach, and over the longer term there is potential for lateral and vertical

erosion if the river has too much transport capacity and too little sediment supply, especially if no mitigation is

provided for the steeper channel gradient after the weir is removed. However studies from previous projects

and rivers show that the estimated bed load within the River Don annually is approximately �##-�,�##m /year.

(high level calculations to support this are presented in Appendix E).

It is noted that there is currently an upstream sediment source which readily supplies sediment downstream as

evidenced by the requirement for annual dredging at the hydro intake upstream of the weir, as noted during

the site walkover and from anecdotal evidence.

8.B Possible Mitigation Measures

A number of mitigation measures are presented below to ensure the stability of the river channel following the

removal of the weir:

.. Stockpiles of removed sediment to re-stock river if required;

�. Sediment removed from main river channel, and placed along the banks and sides of the channel for

the river to naturally work through and transport downstream. Natural variation in flows will allow the

various grades of material to be transported downstream over time providing a more naturally graded

river channel. It is considered that due to the natural supply of sediment that is noted above, only a

certain percentage of the excavated material would require to be retained in the river, estimated to

be approximately �#%. The placement of this sediment will need to be considered so as not to disrupt

the natural bar form and bedform distribution. It can be placed on the outside of meander bends, no

greater than bankfull level where it is most likely to be entrained during higher flows. In the lower

sinuosity sections dredged sediment could be placed on the bed in steeper reaches, but not so that it

smothers the whole bed, or on part of the exposed bar features.

. The downstream pool could be immediately backfilled with material during the weir removal to avoid

any significant steep sections within the channel. Larger boulders in-stream would dissipate the

energy within the flows and the sediment would be redistributed more naturally over time. Boulders

placed at the margins could help stabilise the finer sediments after deposition. Depending on their

placement in the scour pool itself, the boulders may help limit vertical scour by protecting the bed or

may help direct the location of scour.

". Where there could potentially be a step in the river bed where the weir structure once stood, there is

the potential for this to become unstable through erosion. In order to prevent this, the base of the

weir structure could potentially be left in place to provide bed armouring and protection. Additional

steps below the weir could also be introduced to create a step-pool bed morphology in order to

reduce the gradient differential and dissipate energy.



.�

�. In addition, the concrete wingwalls along the length of the existing weir could potentially be retained

to provide bank support.

�. Although not directly linked to the removal of the weir structure, there is the potential to remove a

volume of material from the super-elevated point bar from downstream adjacent to the Waterside

properties. This will allow for a slightly greater channel capacity during higher flows and could

potentially mitigate some flood risk to these properties. It will also allow more natural flow processes

to occur.



.!

5 WEIR REMOVAL OPTIONS APPRAISAL

B.� Removal Options

The below appraisal outlines the options for both the partial and full removal of the Newe Weir structure,

identifying the potential impacts in terms of flood risk, morphology, fish passage and other external receptors.

For each option a number of mitigation measures have been identified which would be recommended to

minimise or prevent many of the proposed detrimental impacts, however this report does not include for any

outline design of these measures.

The estimated extent of sediment behind the weir that is more likely to be mobilised as a consequence of the

two removal options is shown in Figure �... For the partial removal, this extends approximately !#m upstream

and equates to approximately 6##m , while for the full removal option, this extends to approximately �#m

and equates to approximately ",###m .

Figure B.� – Bed sediment immediately upstream of weir for removal options

B.� Partial Removal

B.�.� Extents of works

The partial removal of the weir structure will involve the reducing the height of the weir crest by .m to result in

a drop in height across weir of less than .m (approx. #.!m). The volume of material behind the weir is in the

estimated order of between .-� years’ of natural averaged bedload, so this material could be redistributed

locally within the channel to allow it to be mobilised at different flow rates and mitigate the impact of returning



.6

this material to the river system. This will include partially infilling the pool below the weir with stone from the

weir and sediment from behind the weir to allow a managed transition in bed levels through the structure.

The existing fish pass which is located on the weir would be part-removed with the remaining structure left in-

situ.

The existing wingwalls which are located along the banks of the river at the weir location are to be retained to

provide stability to the banks as the bed and water levels are reduced, and the disused inlet lade located just

downstream of the weir will be backfilled. There is the potential for using the upstream excavated material to

fill this lade.

B.�.� Assessed impacts

The partial removal of the weir will have the following impacts upon the river:

Flood Risk

The hydraulic modelling detailed in Section highlighted that following the partial removal of the weir, there

would be negligible impact on flood risk to any properties up or downstream of the weir.

A marginal increase in the peak out of bank flows on the left bank downstream of the weir was identified

during the modelling of this scenario, however the total volume that was estimated to route out of bank was

similar and so there is not considered to be a significant increase in flood risk to this area. The flood flows

would route through the wooded area on the northern banks in an easterly direction to then flow back into the

river further downstream.

Morphology

Following a partial removal of the weir there will be less of a restriction for sediment transport within the river,

however a constraint will still remain which would restrict bed load transport downstream. As noted in Section

" the River Don appears to have an abundant sediment supply, and so it is considered that retaining a partial

barrier will mean that material would continue to accumulate behind the weir.

Due to the reduced height of the weir, there would be less trapping of finer suspended load and so it is

considered that there would be a slight improvement to the supply of finer sediment downstream.

Fish Passage

As noted above, the partial removal of the weir would retain the remaining fish pass structure. This may

require some ancillary works to ensure that the concrete structure retains its integrity and continues to

function as a fish pass. As such it is considered that there would continue to be an obstacle to migratory fish,

however it would not be as large as the existing weir structure.

Hydro Scheme

Due to the bed levels upstream of the weir being lowered in this scenario, the normal water level immediately

upstream of the weir would also be reduced. This would result in flows which are abstracted for the hydro

scheme being affected. Abstraction for the hydro scheme only occurs when the water within the River Don is

above a certain level, and due to the lowering of the weir, the waters are unlikely to exceed this level with as

much frequency, thus affecting the productivity and effectiveness of the hydro scheme.



�#

In order to mitigate this, the intake location would require to be moved upstream by approximately 6#m.

Further details on the impact to the hydro scheme are included in Section �." below.

B.�.7 Mitigation

In terms of morphology, the excavated gravel from upstream of the partially removed weir could be

redistributed within the local reach, including the reach immediately downstream of the weir to promote

varied bedforms within the channel, however there would only be a limited supply of this material. Other

potential mitigation measures are noted in Section ".�.

As noted above the intake for the hydro scheme will require to be relocated further upstream and based on

the estimated gradient of the river bed post-completion, it is estimated that the intake would require to be

shifted approximately 6#m upstream. Further details are included in Section �.".

With regards to fish passage, if the head drop across the weir is <.m and spread over .#-.�m, then this should

not present a major obstacle to fish. There may be a requirement for some designed placement of stone (from

the weir) to below the removed weir to create individual drops of < #. m.

B.7 Full removal

B.7.� Extents of works

The full removal of the weir will involve the demolition of the concrete structure across the full width of the

channel, including the fish pass, as well as the regrading of the channel bed up and downstream. The

immediate influence of the weir is expected to extend approximately �#m upstream and this reach would

require local adjustment of the channel bed and redistribution of sediment. This would include partial infilling

of the downstream pool along with heavier material from the weir to provide a smoother transition through

former weir footprint and allow natural sediment redistribution during higher flows. It is anticipated that the

concrete sides to the weir structure would be retained following the removal of the weir to provided support

to the banks through this location. The toe of weir would also be retained within the channel to provide bed

protection where there is anticipated to be local steepening of the channel gradient where the weir once

stood. Steps in the channel bed could also be introduced which would reduce the gradient differential.

Given the expected volume of sediment behind the weir, it is expected that only around �#% may be directly

retained within the channel, which is in the estimated order of between .-.# years’ of natural averaged

bedload. The remained of the material could be stored on the bankside and re-introduced to the river over a

longer time period, or disposed off site.

B.7.� Assessed impact

The full removal of the weir would have the following impacts upon the river:

Flood Risk

The hydraulic modelling detailed in Section highlighted that following the full removal of the weir, there

would be negligible impact on flood risk to any properties up or downstream of the weir.

A marginal increase in the peak out of bank flows on the left (northern) bank upstream of the weir was

identified during the modelling of this scenario, however there was also an increase in the flow from the



�.

floodplain back into the river further downstream and so it is considered that demonstrated an increase in the

floodplain flows. These flows would only affect the agricultural land to the north and not any residential

properties.

Morphology

The full removal of the weir structure would allow for a full range of suspended load and bed load sediment to

be transported downstream, promoting a more varied channel morphology. There would be a short term local

adjustment while the bed adjusted and this would depend on the amount of sediment available within the

channel for re-working.

Finer sediment which would have once been trapped behind the weir structure would pass downstream to the

reach between the weir and the Bridge of Newe. This will result in a broader range of sediment grain sizes with

diverse bed and bar forms. As a result of the varied channel morphology there is likely to be an increase in in-

stream channel habitat variability which is beneficial to in-channel biota.

Fish Passage

Removal of the full height of the weir will ensure that any restriction to the passage of fish has been removed.

Hydro Scheme

As with the partial removal of the weir, the upstream bed levels within the river will be reduced following the

full removal of the weir structure, therefore lowering the water levels. The intake for the hydro scheme will

again be affected by this, however the impact would be greater as the full height of the weir would be

removed. In order to mitigate this, the intake location would require to be moved upstream by approximately

��#m. Further details on the impact to the hydro scheme are included in Section �." below.

B.7.7 Mitigation

Section ".� notes a number of mitigation measures which could be implemented in order to ensure that the

morphology of the river is not detrimentally affected by the removal of the weir. This includes placing the

upstream excavated material along the banks of the river to allow the variation in flows to re-mobilise the

material to provide a naturally graded channel, as well as retaining the base of the weir structure to protect

against bed scour and adding steps, pools and boulders to the channel to dissipate energy.

As noted above, the intake location for the hydro scheme will be affected by the removal of the weir, and so

this will require to be re-located further upstream by approximately ��#m. Further details are present in the

following section.

B.8 Newe Hydro Scheme

The intake for the Newe Hydro Scheme is currently located upstream of the weir, on the left bank, and consists

of a lateral overflow with a trash screen, routing flows into a small section of open channel which then flows

through a sluice gate into a large diameter pipe. This pipeline routes east and connects into the tunnel used by

the historic hydro plant on site and feeds the flows into the power plant approximately ��m to the east.



��

If the weir were to be either partially or fully removed, this would impact upon the intake as water levels in the

river will have been dropped, and so it would require to be re-located further upstream to allow it to be routed

by gravity into the power plant.

Based upon the topographical survey that was undertaken and the subsequent hydraulic model that was

constructed, a long section of the watercourse from the weir structure and upstream was generated and is

presented as Figure �.�.

Figure B.� - River long section upstream of existing weir (not to scale, and with vertical exaggeration)

From study of these it was determined that the minimum intake level is approximately ��.� mAOD, and so

based upon the estimated upstream gradient of the post-full removal river channel, the new intake would

require to be located approximately ��#m upstream of the existing one. In the scenario where the weir would

only be partially removed, the intake would require to be located approximately 6#m further upstream. Figure

�. illustrates the existing and proposed channel bed profile, with the estimated locations of the relocated

hydro intakes and Figure �." shows these locations on plan.

The new intake could be extended using a pipeline as per the existing situation, however this is likely to be an

expensive option as the diameter of the existing pipe is understood to be .,�##mm.

Alternatively the intake could potentially take the form of an open channel routing flows to the hydro plant so

as to reduce the costs of the extended intake, however it would need to be designed to ensure that sediment

from within the river would not route into the hydro scheme.

A more detailed feasibility study would be required in order to determine the optimal location and solution for

the relocated intake, and a technical variation would be required for the Controlled Activities (Scotland)

Regulations (CAR) licence for the abstraction of flows from the river.

Figure B.7 - Revised hydro intake locations



Figure . ‐ Relocated hydro intake location plan



��

6 SUMMARY

This report was undertaken to assess the impact of the removal of the Newe Weir, River Don, on the hydrology

and hydromorphology of the river system, and identify the potential removal options.

Baseline hydrological and hydromorphological assessments were undertaken, in conjunction with a

topographical survey of the weir and surrounding area.

The hydrological assessment included the creation of a .-dimensional hydraulic model which outlined the

existing flood risk to the land and properties in the vicinity of the weir, and this determined that peak flows in

the #.�% AEP event would route out of bank along the majority of the study reach. The results from this

baseline scenario concurred with the extents of flooding shown on the SEPA Online Flood Maps.

The hydromorphological assessment outlined the baseline conditions within the river, noting that the River

Don river valley generally has insignificant stability problems with the stable channel being well-adjusted to the

existing hydrophysiological regimes under the current climate. The stable bed and banks indicate a steady state

sediment balance with the river establishing dynamic equilibrium under the existing conditions.

Two removal options have been highlighted – partial and full removal – and an assessment was undertaken of

the impact of both of these scenarios.

With regards to hydrology and flood risk, the hydraulic model of the river was updated to include the partial or

full removal of the weir and re-run for the peak flow events. This modelling indicated that in both scenarios the

weir removal had little impact upon the extents and severity of any out of bank flooding, with the risk to

properties not being increased. The maximum flood levels adjacent to the properties downstream at Waterside

reduced by a maximum of !mm in both scenarios and so the impact on flood risk is considered to be negligible.

The weir removal will have a greater impact upon the hydromorphology of the river and this assessment

identified the upstream and downstream impacts of both scenarios.

In the partial removal scenario, it was identified that although the lowered weir would remain a constraint

within the river which would restrict bed load transport downstream, there would be a slight improvement to

the supply of finer sediment downstream. It is recommended that material excavated from upstream of the

weir be redistributed within the local reach, including the reach immediately downstream of the weir to

promote varied bedforms within the channel. The lowered weir would also remain a partial obstacle for

migratory fish.

Fully removing the weir was identified to have a positive impact upon the river as it would allow for a full range

of suspended load and bed load sediment to be transported downstream, promoting more varied channel

morphology. As a result of the varied channel morphology there is likely to be an increase in in-stream channel

habitat variability which is beneficial to in-channel biota. The removal of the weir and upstream sediment

would require to be carefully managed however, as removal of all of this material has the potential to deplete

the sediment supply for the downstream reach, and over the longer term there is potential for lateral and

vertical erosion if the river has too much transport capacity and too little sediment supply.

Mitigation measures have been outlined to prevent this occurring including: retaining the base of the weir

structure to protect against bed scour; the placement of boulders to reduce the gradient differential and

dissipate energy; potentially the creation of a step-pool bed morphology; and the re-distribution of the

excavated bed material to the banks and sides of the channel for the river to naturally work through and

transport downstream, promoting a more naturally graded river channel.



��

The potential impact upon the intake for the Newe Hydro has identified that the intake would require to be re-

located upstream by approximately 6# and ��#m in the partial and full removal scenarios respectively.



��

REFERENCES

Kjeldsen, T., Jones, D. & Bayliss, A. (�##!). Improving the FEH statistical procedures for flood frequency

estimation (No. SC#�##�#). Bristol: Environment Agency.

Kondolf, G. M. (.66�). Hungry water: Effects of dams and gravel mining on river channels. Environmental

Management, ��(").

NLS (n.d.). Map images. Edinburgh: National Library of Scotland. Retrieved from http://maps.nls.uk/

WHS (�##6). WINFAP-FEH (Software). Wallingford: Wallingford HydroSolutions Limited.



APPENDICES



A ANNUAL EXCEEDANCE PROBABILITY (AEP) AND RETURN PERIODS

CONVERSION TABLE

Table �: Relationship between annual exceedance probability and return periods

Annual exceedance

probability, AEP (%)

Return period, T (year) Comment

�# � Median annual flood, in the long-term this occurs

every other year, on average.

�# �

.# .#

� �#

. # Typical design standard for urban drainage systems.

� �#

. .##

#.� �## Typical design conditions standard for river or

coastal flooding for most developments. Defines

“functional floodplain” under Scottish Planning

Policy.

#.� �##

#.. .,### Typical design conditions standard for sensitive or

vulnerable developments/contexts.

The annual exceedance probability of particular flood conditions is the chance these conditions (or more

severe) occur in any given year.

The return period of a flood is the long-term average period between flood conditions of such magnitude (or

greater).



B HYDROLOGICAL ANALYSIS

Catchment Descriptors

CATCHMENT NJ 7D8B� ��

AREA .6�.�!��

ALTBAR �..

ASPBAR �6

ASPVAR #..

BFIHOST #."��

DPLBAR .!. �

DPSBAR .!6..

FARL #.66�

FPEXT #.#�6�

FPDBAR #."#

FPLOC #.� !

LDP �.!.

PROPWET #.�

RMED-.H !.!

RMED-.D �.�

RMED-�D �...

SAAR .#��

SAAR".�# ..��

SPRHOST "..�"

URBCONC.66# -666666

URBEXT.66# #.###.

URBLOC.66# -666666

URBCONC�### -666666

URBEXT�### #

URBLOC�### -666666

C -#.#.!�6

D. #.""6�

D� #.�#."!

D #. .�!�

E #.�"!.!

F �.��#6�

C(. km) -#.#.!

D.(. km) #."�

D�(. km) #.�#.

D (. km) #. #�

E(. km) #.��.

F(. km) �..�6



Statistical Analysis

The FEH statistical method has been applied using WINFAP-FEH software (WHS, �##6) and the WINFAP-FEH

v".. data files.

A pooled analysis was undertaken using the catchment descriptors extracted from the FEH web service to NJ

!"�# .��## (catchment area .6�. km�). The results of this analysis are described below.

The QMED (median annual maximum flood) for the catchment to NJ !"�# .��## was calculated from

catchment descriptors as � .�� m /s. A donor transfer was applied using data from the gauging station with

the closed catchment centroid (..## Don @ Bridge of Alford) (Kjeldsen, Jones & Bayliss, �##!), providing a

QMED estimate of ��.�"�m /s.

The details of the pooling group used are shown in Table F. and Table F�. The General Logistic (GL) was found

to be most suitable and was used to develop the growth curve fittings (Table F ). The peak flow estimates are

shown in Table F".

Table F�: Pooling group details – FEH catchment to NJ 7D8B� ��

Site River Don

Changes made to default pooling group None

No of sites in pooling group ."

Total no. of years �"�

Pooling group L-CV #.�

Pooling group L-SKEW #.�.!

Heterogeneity measure (H�) �. !"6(review of pooling group is desirable)

Suitable distributions and goodness of fit General Logistic (#.�"#�)

Table F�: Pooling group details - FEH catchment to NJ 7D8B� ��

Station Distance Years of

data

QMED

AM

L-CV L-SKEW Discordancy

9004 (Bogie @ Redcraig) 0.22 26 31.622 0.312 0.274 0.95

66006 (Elwy @ Pont-y-gwyddel) 0.244 38 73.024 0.187 0.133 0.285

21013 (Gala Water @ Galashiels) 0.26 43 51.535 0.273 0.305 0.634

45005 (Otter @ Dotton) 0.284 50 69.81 0.284 0.413 1.538

12008 (Feugh @ Heugh Head) 0.287 21 141.628 0.201 0.11 0.278

47006 (Lyd @ Lifton Park) 0.334 43 80.468 0.275 0.293 0.47

52005 (Tone @ Bishops Hull) 0.347 51 43.861 0.199 0.076 0.732

9003 (Isla @ Grange) 0.35 47 49.309 0.218 0.148 0.904

21032 (Glen @ Kirknewton) 0.379 44 44.45 0.267 0.236 0.253

203024 (Cusher @ Gamble's Bridge) 0.392 41 49.515 0.134 0.013 1.775

67008 (Alyn @ Pont-y-capel) 0.394 47 22.981 0.184 0.353 2.384

11004 (Urie @ Pitcaple) 0.413 18 21.42 0.306 0.268 0.833

12006 (Gairn @ Invergairn) 0.415 28 59.871 0.202 0.085 0.486

28023 (Wye @ Ashford) 0.425 48 16.528 0.21 0.3 2.479



Table F7: Pooled growth curve - FEH catchment to NJ 7D8B� ��

AEP (%) Growth Factor

�# .

�# .. �6

.# ..��6

" �.#�

� �." "

. �.!�

#.� . .

#.� ".#!�

Table F8: Peak Flow Estimates (m7/s)

AEP (%) FEH catchment to NJ 7D8B� ��

(catchment area �FE.7km�)

�# ��.�"�

."�.#6

#.� ��#.��

Summary of estimate using the Flood Estimation Handbook revitalised flood hydrograph method (ReFH)

Site details

Site description:

Catchment Area (km²): 196.28

None

Site name: Don @ Newe Weir

Easting: 338450

Northing: 812200

Model run: 2 yearSummary of results

Rainfall - FEH 2013 (mm): 23.16

Total Rainfall (mm): 15.47

Peak Rainfall (mm): 4.21 70.33

2150.61

1006.57Total runoff (ML):

Total flow (ML):

Peak flow (m³/s):

Loss model parametersName Value User-defined?

Cini (mm) 124.56 No

Cmax (mm) 399.2 No

Use alpha correction factor No No

Alpha correction factor n/a No

Rainfall parameters (Rainfall - FEH 2013 model)Name Value User-defined?

Duration (hh:mm:ss) 04:30:00 No

Timestep (hh:mm:ss) 00:30:00 No

SCF (Seasonal correction factor) 0.77 No

ARF (Areal reduction factor) 0.87 No

Seasonality Winter n/a

Routing model parameters

ParametersWhere the user has overriden a system-generated value, this original value is shown in square brackets after the value used.* Indicates that the user locked the duration/timestep

UK Design Flood Estimation

Generated on Monday, February 20, 2017 12:21:08 PM by dwarrenPrinted from the ReFH Flood Modelling software package, version 2.2.6029.28099

Checksum: 3A08-A285

Country: Scotland

Using plot scale calculations: No

Printed from the ReFH Flood Modelling software package, version 2.2.6029.28099

Page 1 of 5

Name Value User-defined?Tp (hr) 2.39 No

Up 0.65 No

Uk 0.8 No

Name Value User-defined?

BF0 (m³/s) 8.51 No

BL (hr) 35.37 No

BR 1.14 No

Baseflow model parameters

Name Value User-defined?Urban area (km²) 0 No

Urbext 2000 0 No

Impervious runoff factor 0.7 No

Imperviousness factor 0.3 No

Tp scaling factor 0.5 No

Sewered area (km²) 0.00 Yes

Sewer capacity (m³/s) 0.00 Yes

Urbanisation parameters


Page 2 of 5

Time (hh:mm:ss)

Rain (mm)

Sewer Loss (mm)

Net Rain (mm)

Runoff (m³/s)

Baseflow (m³/s)

Total Flow (m³/s)

00:00:00 0.442 0.000 0.138 0.000 8.506 8.506

00:30:00 0.830 0.000 0.261 0.215 8.388 8.604

01:00:00 1.543 0.000 0.489 1.051 8.281 9.332

01:30:00 2.818 0.000 0.909 3.054 8.197 11.251

02:00:00 4.208 0.000 1.395 7.233 8.165 15.398

02:30:00 2.818 0.000 0.959 14.980 8.228 23.208

03:00:00 1.543 0.000 0.533 25.895 8.440 34.335

03:30:00 0.830 0.000 0.289 37.997 8.833 46.829

04:00:00 0.442 0.000 0.155 49.247 9.407 58.654

04:30:00 0.000 0.000 0.000 57.258 10.127 67.385

05:00:00 0.000 0.000 0.000 59.413 10.918 70.331

05:30:00 0.000 0.000 0.000 56.383 11.692 68.074

06:00:00 0.000 0.000 0.000 50.397 12.382 62.779

06:30:00 0.000 0.000 0.000 43.148 12.956 56.104

07:00:00 0.000 0.000 0.000 35.866 13.406 49.272

07:30:00 0.000 0.000 0.000 29.649 13.742 43.391

08:00:00 0.000 0.000 0.000 24.424 13.982 38.406

08:30:00 0.000 0.000 0.000 19.776 14.139 33.916

09:00:00 0.000 0.000 0.000 15.484 14.223 29.706

09:30:00 0.000 0.000 0.000 11.497 14.239 25.736

10:00:00 0.000 0.000 0.000 7.808 14.193 22.001

10:30:00 0.000 0.000 0.000 4.632 14.094 18.726

11:00:00 0.000 0.000 0.000 2.325 13.951 16.277

11:30:00 0.000 0.000 0.000 1.017 13.782 14.800

12:00:00 0.000 0.000 0.000 0.368 13.600 13.968

12:30:00 0.000 0.000 0.000 0.086 13.413 13.498

13:00:00 0.000 0.000 0.000 0.002 13.225 13.227

13:30:00 0.000 0.000 0.000 0.000 13.039 13.039

14:00:00 0.000 0.000 0.000 0.000 12.856 12.856

14:30:00 0.000 0.000 0.000 0.000 12.676 12.676

15:00:00 0.000 0.000 0.000 0.000 12.498 12.498

15:30:00 0.000 0.000 0.000 0.000 12.322 12.322

16:00:00 0.000 0.000 0.000 0.000 12.150 12.150

16:30:00 0.000 0.000 0.000 0.000 11.979 11.979

17:00:00 0.000 0.000 0.000 0.000 11.811 11.811

Time series data


Page 3 of 5

Time (hh:mm:ss)

Rain (mm)

Sewer Loss (mm)

Net Rain (mm)

Runoff (m³/s)

Baseflow (m³/s)

Total Flow (m³/s)

17:30:00 0.000 0.000 0.000 0.000 11.645 11.645

18:00:00 0.000 0.000 0.000 0.000 11.482 11.482

18:30:00 0.000 0.000 0.000 0.000 11.320 11.320

19:00:00 0.000 0.000 0.000 0.000 11.161 11.161

19:30:00 0.000 0.000 0.000 0.000 11.005 11.005

20:00:00 0.000 0.000 0.000 0.000 10.850 10.850

20:30:00 0.000 0.000 0.000 0.000 10.698 10.698

21:00:00 0.000 0.000 0.000 0.000 10.548 10.548

21:30:00 0.000 0.000 0.000 0.000 10.400 10.400

22:00:00 0.000 0.000 0.000 0.000 10.254 10.254

22:30:00 0.000 0.000 0.000 0.000 10.110 10.110

23:00:00 0.000 0.000 0.000 0.000 9.968 9.968

23:30:00 0.000 0.000 0.000 0.000 9.828 9.828

24:00:00 0.000 0.000 0.000 0.000 9.690 9.690

24:30:00 0.000 0.000 0.000 0.000 9.554 9.554

25:00:00 0.000 0.000 0.000 0.000 9.420 9.420

25:30:00 0.000 0.000 0.000 0.000 9.288 9.288

26:00:00 0.000 0.000 0.000 0.000 9.157 9.157

26:30:00 0.000 0.000 0.000 0.000 9.029 9.029

27:00:00 0.000 0.000 0.000 0.000 8.902 8.902

27:30:00 0.000 0.000 0.000 0.000 8.777 8.777

28:00:00 0.000 0.000 0.000 0.000 8.654 8.654


Page 4 of 5

AppendixCatchment descriptors

Name Value User-defined value used?

Area (km²) 196.28 No

ALTBAR 511 No

ASPBAR 79 No

ASPVAR 0.1 No

BFIHOST 0.47 No

DPLBAR (km) 18.36 No

DPSBAR (mkm-¹) 189.1 No

FARL 1 No

LDP 36.81 No

PROPWET (mm) 0.63 No

RMED1H 8.8 No

RMED1D 36.7 No

RMED2D 51.1 No

SAAR (mm) 1057 No

SAAR4170 (mm) 1162 No

SPRHOST 41.24 No

Urbext2000 0 No

Urbext1990 0 No

URBCONC 0 No

URBLOC 0 No

Urban Area (km²) 0 No

DDF parameter C -0.02 No

DDF parameter D1 0.45 No



DDF parameter E 0.25 No

DDF parameter F 2.27 No

DDF parameter C (1km grid value) -0.02 No

DDF parameter D1 (1km grid value) 0.46 No



DDF parameter E (1km grid value) 0.25 No

DDF parameter F (1km grid value) 2.17 No


Page 5 of 5


Site details

Site description:


None


Easting: 338450

Northing: 812200





4903.70


Total flow (ML):

Peak flow (m³/s):


Cini (mm) 124.56 No

Cmax (mm) 399.2 No













Checksum: 3A08-A285

Country: Scotland



Page 1 of 6


Up 0.65 No

Uk 0.8 No


BF0 (m³/s) 8.51 No

BL (hr) 35.37 No

BR 1.14 No



Urbext 2000 0 No








Page 2 of 6

Time (hh:mm:ss)

Rain (mm)

Sewer Loss (mm)

Net Rain (mm)

Runoff (m³/s)

Baseflow (m³/s)

Total Flow (m³/s)

00:00:00 0.944 0.000 0.296 0.000 8.506 8.506

00:30:00 1.772 0.000 0.561 0.460 8.390 8.851

01:00:00 3.295 0.000 1.064 2.254 8.294 10.549

01:30:00 6.019 0.000 2.014 6.577 8.249 14.826

02:00:00 8.988 0.000 3.177 15.691 8.311 24.002

02:30:00 6.019 0.000 2.240 32.845 8.583 41.428

03:00:00 3.295 0.000 1.265 57.370 9.185 66.555

03:30:00 1.772 0.000 0.692 84.908 10.195 95.103

04:00:00 0.944 0.000 0.372 110.858 11.619 122.477

04:30:00 0.000 0.000 0.000 129.774 13.381 143.155

05:00:00 0.000 0.000 0.000 135.455 15.315 150.771

05:30:00 0.000 0.000 0.000 129.115 17.217 146.332

06:00:00 0.000 0.000 0.000 115.753 18.934 134.687

06:30:00 0.000 0.000 0.000 99.280 20.389 119.668

07:00:00 0.000 0.000 0.000 82.569 21.557 104.126

07:30:00 0.000 0.000 0.000 68.255 22.461 90.715

08:00:00 0.000 0.000 0.000 56.247 23.141 79.388

08:30:00 0.000 0.000 0.000 45.605 23.631 69.236

09:00:00 0.000 0.000 0.000 35.800 23.951 59.751

09:30:00 0.000 0.000 0.000 26.692 24.114 50.807

10:00:00 0.000 0.000 0.000 18.234 24.135 42.369

10:30:00 0.000 0.000 0.000 10.902 24.029 34.932

11:00:00 0.000 0.000 0.000 5.520 23.823 29.344

11:30:00 0.000 0.000 0.000 2.429 23.552 25.982

12:00:00 0.000 0.000 0.000 0.883 23.248 24.131

12:30:00 0.000 0.000 0.000 0.206 22.931 23.137

13:00:00 0.000 0.000 0.000 0.004 22.610 22.614

13:30:00 0.000 0.000 0.000 0.000 22.293 22.293

14:00:00 0.000 0.000 0.000 0.000 21.980 21.980

14:30:00 0.000 0.000 0.000 0.000 21.672 21.672

15:00:00 0.000 0.000 0.000 0.000 21.367 21.367

15:30:00 0.000 0.000 0.000 0.000 21.067 21.067

16:00:00 0.000 0.000 0.000 0.000 20.772 20.772

16:30:00 0.000 0.000 0.000 0.000 20.480 20.480

17:00:00 0.000 0.000 0.000 0.000 20.193 20.193

Time series data


Page 3 of 6

Time (hh:mm:ss)

Rain (mm)

Sewer Loss (mm)

Net Rain (mm)

Runoff (m³/s)

Baseflow (m³/s)

Total Flow (m³/s)

17:30:00 0.000 0.000 0.000 0.000 19.909 19.909

18:00:00 0.000 0.000 0.000 0.000 19.630 19.630

18:30:00 0.000 0.000 0.000 0.000 19.354 19.354

19:00:00 0.000 0.000 0.000 0.000 19.082 19.082

19:30:00 0.000 0.000 0.000 0.000 18.815 18.815

20:00:00 0.000 0.000 0.000 0.000 18.550 18.550

20:30:00 0.000 0.000 0.000 0.000 18.290 18.290

21:00:00 0.000 0.000 0.000 0.000 18.033 18.033

21:30:00 0.000 0.000 0.000 0.000 17.780 17.780

22:00:00 0.000 0.000 0.000 0.000 17.531 17.531

22:30:00 0.000 0.000 0.000 0.000 17.285 17.285

23:00:00 0.000 0.000 0.000 0.000 17.042 17.042

23:30:00 0.000 0.000 0.000 0.000 16.803 16.803

24:00:00 0.000 0.000 0.000 0.000 16.567 16.567

24:30:00 0.000 0.000 0.000 0.000 16.334 16.334

25:00:00 0.000 0.000 0.000 0.000 16.105 16.105

25:30:00 0.000 0.000 0.000 0.000 15.879 15.879

26:00:00 0.000 0.000 0.000 0.000 15.656 15.656

26:30:00 0.000 0.000 0.000 0.000 15.436 15.436

27:00:00 0.000 0.000 0.000 0.000 15.220 15.220

27:30:00 0.000 0.000 0.000 0.000 15.006 15.006

28:00:00 0.000 0.000 0.000 0.000 14.795 14.795

28:30:00 0.000 0.000 0.000 0.000 14.588 14.588

29:00:00 0.000 0.000 0.000 0.000 14.383 14.383

29:30:00 0.000 0.000 0.000 0.000 14.181 14.181

30:00:00 0.000 0.000 0.000 0.000 13.982 13.982

30:30:00 0.000 0.000 0.000 0.000 13.786 13.786

31:00:00 0.000 0.000 0.000 0.000 13.592 13.592

31:30:00 0.000 0.000 0.000 0.000 13.401 13.401

32:00:00 0.000 0.000 0.000 0.000 13.213 13.213

32:30:00 0.000 0.000 0.000 0.000 13.028 13.028

33:00:00 0.000 0.000 0.000 0.000 12.845 12.845

33:30:00 0.000 0.000 0.000 0.000 12.665 12.665

34:00:00 0.000 0.000 0.000 0.000 12.487 12.487

34:30:00 0.000 0.000 0.000 0.000 12.312 12.312

35:00:00 0.000 0.000 0.000 0.000 12.139 12.139


Page 4 of 6

Time (hh:mm:ss)

Rain (mm)

Sewer Loss (mm)

Net Rain (mm)

Runoff (m³/s)

Baseflow (m³/s)

Total Flow (m³/s)

35:30:00 0.000 0.000 0.000 0.000 11.968 11.968

36:00:00 0.000 0.000 0.000 0.000 11.800 11.800

36:30:00 0.000 0.000 0.000 0.000 11.635 11.635

37:00:00 0.000 0.000 0.000 0.000 11.471 11.471

37:30:00 0.000 0.000 0.000 0.000 11.310 11.310

38:00:00 0.000 0.000 0.000 0.000 11.152 11.152

38:30:00 0.000 0.000 0.000 0.000 10.995 10.995

39:00:00 0.000 0.000 0.000 0.000 10.841 10.841

39:30:00 0.000 0.000 0.000 0.000 10.688 10.688

40:00:00 0.000 0.000 0.000 0.000 10.538 10.538

40:30:00 0.000 0.000 0.000 0.000 10.391 10.391

41:00:00 0.000 0.000 0.000 0.000 10.245 10.245

41:30:00 0.000 0.000 0.000 0.000 10.101 10.101

42:00:00 0.000 0.000 0.000 0.000 9.959 9.959

42:30:00 0.000 0.000 0.000 0.000 9.819 9.819

43:00:00 0.000 0.000 0.000 0.000 9.681 9.681

43:30:00 0.000 0.000 0.000 0.000 9.546 9.546

44:00:00 0.000 0.000 0.000 0.000 9.412 9.412

44:30:00 0.000 0.000 0.000 0.000 9.279 9.279

45:00:00 0.000 0.000 0.000 0.000 9.149 9.149

45:30:00 0.000 0.000 0.000 0.000 9.021 9.021

46:00:00 0.000 0.000 0.000 0.000 8.894 8.894

46:30:00 0.000 0.000 0.000 0.000 8.769 8.769

47:00:00 0.000 0.000 0.000 0.000 8.646 8.646


Page 5 of 6




ALTBAR 511 No

ASPBAR 79 No

ASPVAR 0.1 No

BFIHOST 0.47 No



FARL 1 No

LDP 36.81 No


RMED1H 8.8 No

RMED1D 36.7 No

RMED2D 51.1 No

SAAR (mm) 1057 No

SAAR4170 (mm) 1162 No

SPRHOST 41.24 No

Urbext2000 0 No

Urbext1990 0 No

URBCONC 0 No

URBLOC 0 No















Page 6 of 6


Site details

Site description:


None


Easting: 338450

Northing: 812200





6998.01


Total flow (ML):

Peak flow (m³/s):


Cini (mm) 124.56 No

Cmax (mm) 399.2 No













Checksum: 3A08-A285

Country: Scotland



Page 1 of 7


Up 0.65 No

Uk 0.8 No


BF0 (m³/s) 8.51 No

BL (hr) 35.37 No

BR 1.14 No



Urbext 2000 0 No








Page 2 of 7

Time (hh:mm:ss)

Rain (mm)

Sewer Loss (mm)

Net Rain (mm)

Runoff (m³/s)

Baseflow (m³/s)

Total Flow (m³/s)

00:00:00 1.290 0.000 0.405 0.000 8.506 8.506

00:30:00 2.421 0.000 0.771 0.630 8.392 9.022

01:00:00 4.502 0.000 1.472 3.089 8.304 11.393

01:30:00 8.223 0.000 2.820 9.038 8.284 17.322

02:00:00 12.280 0.000 4.526 21.665 8.414 30.079

02:30:00 8.223 0.000 3.242 45.674 8.835 54.509

03:00:00 4.502 0.000 1.847 80.323 9.720 90.043

03:30:00 2.421 0.000 1.014 119.538 11.183 130.721

04:00:00 1.290 0.000 0.547 156.801 13.238 170.039

04:30:00 0.000 0.000 0.000 184.344 15.782 200.126

05:00:00 0.000 0.000 0.000 193.122 18.580 211.702

05:30:00 0.000 0.000 0.000 184.581 21.341 205.922

06:00:00 0.000 0.000 0.000 165.783 23.845 189.628

06:30:00 0.000 0.000 0.000 142.344 25.975 168.319

07:00:00 0.000 0.000 0.000 118.424 27.696 146.120

07:30:00 0.000 0.000 0.000 97.892 29.038 126.929

08:00:00 0.000 0.000 0.000 80.688 30.058 110.746

08:30:00 0.000 0.000 0.000 65.476 30.806 96.281

09:00:00 0.000 0.000 0.000 51.481 31.309 82.789

09:30:00 0.000 0.000 0.000 38.479 31.589 70.068

10:00:00 0.000 0.000 0.000 26.379 31.664 58.043

10:30:00 0.000 0.000 0.000 15.845 31.557 47.402

11:00:00 0.000 0.000 0.000 8.064 31.305 39.369

11:30:00 0.000 0.000 0.000 3.561 30.959 34.519

12:00:00 0.000 0.000 0.000 1.296 30.563 31.859

12:30:00 0.000 0.000 0.000 0.303 30.147 30.450

13:00:00 0.000 0.000 0.000 0.006 29.726 29.732

13:30:00 0.000 0.000 0.000 0.000 29.309 29.309

14:00:00 0.000 0.000 0.000 0.000 28.897 28.897

14:30:00 0.000 0.000 0.000 0.000 28.492 28.492

15:00:00 0.000 0.000 0.000 0.000 28.092 28.092

15:30:00 0.000 0.000 0.000 0.000 27.697 27.697

16:00:00 0.000 0.000 0.000 0.000 27.309 27.309

16:30:00 0.000 0.000 0.000 0.000 26.925 26.925

17:00:00 0.000 0.000 0.000 0.000 26.547 26.547

Time series data


Page 3 of 7

Time (hh:mm:ss)

Rain (mm)

Sewer Loss (mm)

Net Rain (mm)

Runoff (m³/s)

Baseflow (m³/s)

Total Flow (m³/s)

17:30:00 0.000 0.000 0.000 0.000 26.175 26.175

18:00:00 0.000 0.000 0.000 0.000 25.807 25.807

18:30:00 0.000 0.000 0.000 0.000 25.445 25.445

19:00:00 0.000 0.000 0.000 0.000 25.088 25.088

19:30:00 0.000 0.000 0.000 0.000 24.736 24.736

20:00:00 0.000 0.000 0.000 0.000 24.388 24.388

20:30:00 0.000 0.000 0.000 0.000 24.046 24.046

21:00:00 0.000 0.000 0.000 0.000 23.709 23.709

21:30:00 0.000 0.000 0.000 0.000 23.376 23.376

22:00:00 0.000 0.000 0.000 0.000 23.048 23.048

22:30:00 0.000 0.000 0.000 0.000 22.724 22.724

23:00:00 0.000 0.000 0.000 0.000 22.405 22.405

23:30:00 0.000 0.000 0.000 0.000 22.091 22.091

24:00:00 0.000 0.000 0.000 0.000 21.781 21.781

24:30:00 0.000 0.000 0.000 0.000 21.475 21.475

25:00:00 0.000 0.000 0.000 0.000 21.173 21.173

25:30:00 0.000 0.000 0.000 0.000 20.876 20.876

26:00:00 0.000 0.000 0.000 0.000 20.583 20.583

26:30:00 0.000 0.000 0.000 0.000 20.294 20.294

27:00:00 0.000 0.000 0.000 0.000 20.009 20.009

27:30:00 0.000 0.000 0.000 0.000 19.728 19.728

28:00:00 0.000 0.000 0.000 0.000 19.452 19.452

28:30:00 0.000 0.000 0.000 0.000 19.178 19.178

29:00:00 0.000 0.000 0.000 0.000 18.909 18.909

29:30:00 0.000 0.000 0.000 0.000 18.644 18.644

30:00:00 0.000 0.000 0.000 0.000 18.382 18.382

30:30:00 0.000 0.000 0.000 0.000 18.124 18.124

31:00:00 0.000 0.000 0.000 0.000 17.870 17.870

31:30:00 0.000 0.000 0.000 0.000 17.619 17.619

32:00:00 0.000 0.000 0.000 0.000 17.372 17.372

32:30:00 0.000 0.000 0.000 0.000 17.128 17.128

33:00:00 0.000 0.000 0.000 0.000 16.887 16.887

33:30:00 0.000 0.000 0.000 0.000 16.650 16.650

34:00:00 0.000 0.000 0.000 0.000 16.416 16.416

34:30:00 0.000 0.000 0.000 0.000 16.186 16.186

35:00:00 0.000 0.000 0.000 0.000 15.959 15.959


Page 4 of 7

Time (hh:mm:ss)

Rain (mm)

Sewer Loss (mm)

Net Rain (mm)

Runoff (m³/s)

Baseflow (m³/s)

Total Flow (m³/s)

35:30:00 0.000 0.000 0.000 0.000 15.735 15.735

36:00:00 0.000 0.000 0.000 0.000 15.514 15.514

36:30:00 0.000 0.000 0.000 0.000 15.296 15.296

37:00:00 0.000 0.000 0.000 0.000 15.081 15.081

37:30:00 0.000 0.000 0.000 0.000 14.870 14.870

38:00:00 0.000 0.000 0.000 0.000 14.661 14.661

38:30:00 0.000 0.000 0.000 0.000 14.455 14.455

39:00:00 0.000 0.000 0.000 0.000 14.252 14.252

39:30:00 0.000 0.000 0.000 0.000 14.052 14.052

40:00:00 0.000 0.000 0.000 0.000 13.855 13.855

40:30:00 0.000 0.000 0.000 0.000 13.661 13.661

41:00:00 0.000 0.000 0.000 0.000 13.469 13.469

41:30:00 0.000 0.000 0.000 0.000 13.280 13.280

42:00:00 0.000 0.000 0.000 0.000 13.093 13.093

42:30:00 0.000 0.000 0.000 0.000 12.909 12.909

43:00:00 0.000 0.000 0.000 0.000 12.728 12.728

43:30:00 0.000 0.000 0.000 0.000 12.550 12.550

44:00:00 0.000 0.000 0.000 0.000 12.373 12.373

44:30:00 0.000 0.000 0.000 0.000 12.200 12.200

45:00:00 0.000 0.000 0.000 0.000 12.029 12.029

45:30:00 0.000 0.000 0.000 0.000 11.860 11.860

46:00:00 0.000 0.000 0.000 0.000 11.693 11.693

46:30:00 0.000 0.000 0.000 0.000 11.529 11.529

47:00:00 0.000 0.000 0.000 0.000 11.367 11.367

47:30:00 0.000 0.000 0.000 0.000 11.208 11.208

48:00:00 0.000 0.000 0.000 0.000 11.050 11.050

48:30:00 0.000 0.000 0.000 0.000 10.895 10.895

49:00:00 0.000 0.000 0.000 0.000 10.742 10.742

49:30:00 0.000 0.000 0.000 0.000 10.591 10.591

50:00:00 0.000 0.000 0.000 0.000 10.443 10.443

50:30:00 0.000 0.000 0.000 0.000 10.296 10.296

51:00:00 0.000 0.000 0.000 0.000 10.152 10.152

51:30:00 0.000 0.000 0.000 0.000 10.009 10.009

52:00:00 0.000 0.000 0.000 0.000 9.869 9.869

52:30:00 0.000 0.000 0.000 0.000 9.730 9.730

53:00:00 0.000 0.000 0.000 0.000 9.594 9.594


Page 5 of 7

Time (hh:mm:ss)

Rain (mm)

Sewer Loss (mm)

Net Rain (mm)

Runoff (m³/s)

Baseflow (m³/s)

Total Flow (m³/s)

53:30:00 0.000 0.000 0.000 0.000 9.459 9.459

54:00:00 0.000 0.000 0.000 0.000 9.326 9.326

54:30:00 0.000 0.000 0.000 0.000 9.195 9.195

55:00:00 0.000 0.000 0.000 0.000 9.066 9.066

55:30:00 0.000 0.000 0.000 0.000 8.939 8.939

56:00:00 0.000 0.000 0.000 0.000 8.813 8.813

56:30:00 0.000 0.000 0.000 0.000 8.690 8.690

57:00:00 0.000 0.000 0.000 0.000 8.568 8.568


Page 6 of 7




ALTBAR 511 No

ASPBAR 79 No

ASPVAR 0.1 No

BFIHOST 0.47 No



FARL 1 No

LDP 36.81 No


RMED1H 8.8 No

RMED1D 36.7 No

RMED2D 51.1 No

SAAR (mm) 1057 No

SAAR4170 (mm) 1162 No

SPRHOST 41.24 No

Urbext2000 0 No

Urbext1990 0 No

URBCONC 0 No

URBLOC 0 No















Page 7 of 7



C SITE PHOTOGRAPHS

Number Photo Description

.

Looking

upstream from

the upstream

extent of the

study reach.

�

Looking

downstream in

the upstream

part of the

study reach,

showing point

bar feature.




River meander,

looking

upstream.

"

Looking

downstream on

river channel,

approaching the

weir location.

�

Hydro intake on

LHB

immediately

upstream of the

weir. (looking

upstream)




�

Newe Weir with

existing fish

ladder and

downstream

section of

channel.

�

Looking

downstream

from the weir.

Dense forestry

are on the LHB

and the houses

of Waterside

are visible in the

distance on the

RHB.

!

Significant bank

protection at

meander

adjacent to the

houses on

Waterside Road.

Looking

downstream,

protection on

RHB.




6

Looking

downstream

towards Bridge

of Newe. Large

elevated point

bar on LHB.

.#

Looking

upstream from

Bridge of Newe

at hydro

outflow

confluence.

River Don

channel to the

left of image,

outflow channel

from the hydro

plant to the

right.

..

Burn of Deochry

flowing into

River Dee (far

right on image)

immediately

downstream of

outfall channel

from Hydro

plant. Finer

sediment can be

seen in the bed

from this

channel as

opposed to the

coarser bed

material in the

River Dee on

the left.




.�

Bed of River

Don

immediately

downstream of

Bridge of Newe,

showing fine

sandy sediment,

and also dead

fish.



D HYDRAULIC MODELLING RESULTS

Don_0000

Don_0249

Don_0249!

Don_0249!!

Don_0562

Don_0562!

Don_0562!!

Don_0938

Don_0938!Don_0938!!

Don_1097

Don_1207

Don_1256

Don_1380

Don_1650

Don_1716Don_1856

Don_1946

Don_2195Don_2195!

Don_2354

Don_2653

Don_2653!

Network - River DonNewe Weir

Powered by

Map Centre Coords x: 337224, y: 812126Date Printed: 05/05/2017Scale 1:3000

100m

Scenario A Results

Node Max Flow (m3/s) Max Stage (m AD) Max Velocity (m/s)

Don_0000 207.709 259.589 3.023

Don_0249 207.683 261.27 3.543

Don_0249! 207.713 260.025 3.824

Don_0249!! 207.677 260.69 3.85

Don_0562 209.991 262.972 3.409

Don_0562! 207.664 261.811 3.693

Don_0562!! 210.021 262.57 3.51

Don_0938 31.578 263.649 1.897

Don_0938! 33.587 264.098 1.552

Don_0938!! 31.689 263.973 2.478

Don_1097 146.199 265.136 2.552

Don_1097! 146.203 263.495 6.502

Don_1207 217.234 264.745 7.313

Don_1207! 217.234 264.967 5.641

Don_1224 217.237 265.349 7.559

Don_1256 217.236 266.022 4.87

Don_1380 219.016 266.772 3.58

Don_1511 217.272 267.218 3.112

Don_1650 139.83 268.248 2.417

Don_1716 141.689 268.454 2.162

Don_1745 141.976 268.509 2.047

Don_1778 218.642 269.755 2.42

Don_1778! 218.642 267.712 3.837

Don_1856 218.629 269.93 2.252

Don_1946 32.246 270.657 1.328

Don_2195 32.728 270.608 1.684

Don_2195! 32.269 270.644 1.61

Don_2354 61.611 270.662 2.551

Don_2653 71.871 272.378 2.194

Don_2653! 61.516 271.029 2.254

Don_2899 45.722 273.849 1.841

Don_2994 152.823 273.492 6.992

Don_3129 220.67 276.055 3.556

Don_3129! 152.823 273.492 7.236

Scenario B Results


Don_0000 211.712 259.611 3.03

Don_0249 211.721 261.297 3.569

Don_0249! 211.713 260.049 3.855

Don_0249!! 211.698 260.716 3.88

Don_0562 212.456 263.004 3.418

Don_0562! 211.742 261.838 3.726

Don_0562!! 212.424 262.604 3.493

Don_0938 31.503 263.692 1.908

Don_0938! 33.311 264.136 1.558

Don_0938!! 31.453 264.006 2.471

Don_1097 147.624 265.127 2.586

Don_1097! 147.815 263.52 6.201

Don_1207 219.446 264.702 7.165

Don_1207! 219.446 264.934 5.549

Don_1224 219.485 265.271 7.474

Don_1256 219.361 266.011 4.63

Don_1380 219.79 266.757 3.456

Don_1511 219.482 267.21 3.028

Don_1650 137.575 268.28 2.401

Don_1716 137.812 268.465 2.194

Don_1745 138.327 268.509 2.482

Don_1778 219.845 268.487 4.223

Don_1778! 219.845 267.843 4.699

Don_1856 219.809 269.093 3.671

Don_1946 30.81 270.58 1.34

Don_2195 31.004 270.538 1.654

Don_2195! 30.485 270.568 1.578

Don_2354 63.254 270.592 2.57

Don_2653 72.606 272.381 2.241

Don_2653! 61.174 271.026 2.346

Don_2899 50.374 273.847 1.834

Don_2994 152.294 273.497 6.981

Don_3129 220.67 276.052 3.551

Don_3129! 152.294 273.497 7.226

Scenario C Results


Don_0000 212.566 259.616 3.031

Don_0249 212.547 261.303 3.574

Don_0249! 212.565 260.054 3.861

Don_0249!! 212.556 260.721 3.886

Don_0562 213.423 263.011 3.424

Don_0562! 212.537 261.844 3.732

Don_0562!! 213.394 262.61 3.488

Don_0938 33.539 263.7 2.026

Don_0938! 33.336 264.144 1.552

Don_0938!! 34.573 264.015 2.598

Don_1097 148.179 265.112 2.591

Don_1097! 148.179 263.521 6.163

Don_1207 220.313 264.706 7.158

Don_1207! 220.313 264.93 5.545

Don_1224 220.302 265.273 7.434

Don_1256 220.278 266.009 4.632

Don_1380 220.298 266.761 3.444

Don_1511 220.334 267.212 3.031

Don_1650 138.677 268.286 2.52

Don_1716 138.714 268.472 2.219

Don_1745 138.96 268.508 2.789

Don_1778 220.748 267.933 3.864

Don_1778! 220.802 267.844 4.246

Don_1856 220.562 268.706 4.53

Don_1946 31.696 270.508 1.114

Don_2195 27.697 270.267 2.025

Don_2195! 28.801 270.464 2.099

Don_2354 61.81 270.494 2.931

Don_2653 73.053 272.38 2.252

Don_2653! 62.347 271.034 2.322

Don_2899 49.343 273.848 1.939

Don_2994 153.614 273.502 7.005

Don_3129 220.67 276.061 3.567

Don_3129! 153.614 273.502 7.25

Scenario A Scenario B Scenario C

Node Max Stage (m AD) Max Stage (m AD) Max Stage (m AD)

Don_0000 259.589 259.611 0.022 259.616 0.027

Don_0249! 260.025 260.049 0.024 260.054 0.029

Don_0249!! 260.69 260.716 0.026 260.721 0.031

Don_0249 261.27 261.297 0.027 261.303 0.033

Don_0562! 261.811 261.838 0.027 261.844 0.033

Don_0562!! 262.57 262.604 0.034 262.61 0.04

Don_0562 262.972 263.004 0.032 263.011 0.039

Don_0938! 264.098 264.136 0.038 264.144 0.046

Don_0938!! 263.973 264.006 0.033 264.015 0.042

Don_0938 263.649 263.692 0.043 263.7 0.051

Don_1097! 263.495 263.52 0.025 263.521 0.026

Don_1097 265.136 265.127 -0.009 265.112 -0.024

Don_1207! 264.967 264.934 -0.033 264.93 -0.037

Don_1207 264.745 264.702 -0.043 264.706 -0.039

Don_1224 265.349 265.271 -0.078 265.273 -0.076

Don_1256 266.022 266.011 -0.011 266.009 -0.013

Don_1380 266.772 266.757 -0.015 266.761 -0.011

Don_1511 267.218 267.21 -0.008 267.212 -0.006

Don_1650 268.248 268.28 0.032 268.286 0.038

Don_1716 268.454 268.465 0.011 268.472 0.018

Don_1745 268.509 268.509 0 268.508 -0.001

Don_1778! 267.712 267.843 0.131 267.844 0.132

Don_1778 (W) 269.755 268.487 -1.268 267.933 -1.822

Don_1856 269.93 269.093 -0.837 268.706 -1.224

Don_1946 270.657 270.58 -0.077 270.508 -0.149

Don_2195! 270.644 270.568 -0.076 270.464 -0.18

Don_2195 270.608 270.538 -0.07 270.267 -0.341

Don_2354 270.662 270.592 -0.07 270.494 -0.168

Don_2653! 271.029 271.026 -0.003 271.034 0.005

Don_2653 272.378 272.381 0.003 272.38 0.002

Don_2899 273.849 273.847 -0.002 273.848 -0.001

Don_2994 273.492 273.497 0.005 273.502 0.01

Don_3129! 273.492 273.497 0.005 273.502 0.01

Don_3129 276.055 276.052 -0.003 276.061 0.006



E SEDIMENT REGIME CALCULATIONS

River Don catchment area to the Newe Weir = .6� km�

Applying calculations based upon equations from NRA .66. – Provided in the Guidebook of Applied

Geomorphology which state that for catchments greater than .##km� the following equation can be applied:

�.�CA...�

= �.�*.6�...�

= .,."# t/yr = E77m7/yr

Regional variations of fluvial sediment yield in eastern Scotland (McManus & Duck) notes that there is a

general trend of "-�## tonnes/km�/year. This would result in a total sediment yield of approximately " �-

�.,�� m /yr. However, based upon Table . from the above publication, the River Don has an approximate

sediment yield of .!." t/km�/yr. For the catchment to the Newe Weir this would result in approximately ,�#�

t/year, or �,## m /yr. This figure is the total load and includes both suspended and bed load. The bed load is

then estimated to be approximately .#% of total load. => ��m7/yr

EnviroCentre have undertaken analysis into the infilling of a former in-stream sand and gravel quarry on the

River Clyde. The former quarry extent has been compared to the present development of the alluvial fan at the

inflow to the former quarry pool. This volume of sediment has been calculated and an annual sediment load

estimated from the period since quarrying ceased. The findings indicate an annualised bedload sediment

accumulation of �,!�. m /yr from a contributing catchment area of "��km

�. Scaling this to the catchment of

the Don @ Newe Weir (.6�km�) this would result in a yield of �,8D�m

7/yr.

The above methods of prediction would indicate an annualised bedload transport in the range of �� – �,B��

m7/yr.



F TOPOGRAPHICAL SURVEY

2

6

6

.

7

7

2

6

6

.

8

6

2

6

6

.

9

3

2

6

6

.

6

7

2

6

6

.

2

4

2

6

5

.

8

7

2

6

5

.

0

02

6

4

.

7

6

2

6

4

.

6

4

264.96

2

6

4

.

5

3

2

6

4

.

4

4

2

6

4

.

5

9

2

6

4

.

8

3

2

6

5

.

0

0

2

6

5

.

2

1

2

6

6

.

0

2

2

6

6

.

5

0

2

6

6

.

4

2

2

6

6

.

6

5

2

6

7

.

0

1

2

6

6

.

7

2

2

6

6

.

6

5

2

6

6

.

7

9

2

6

6

.

9

1

2

6

6

.

0

8

2

6

5

.

9

5

2

6

6

.

9

1

2

6

7

.

4

1

2

6

7

.

5

3

2

6

7

.

4

2

2

6

6

.

4

5

2

6

6

.

6

2

2

6

7

.

0

7

2

6

7

.

2

4

2

6

7

.

0

6

2

6

6

.

6

1

2

6

5

.5

9

265.70

2

6

5

.4

8

2

6

5

.3

0

2

6

5

.3

9

2

6

5

.4

6

2

6

5

.4

6

2

6

5

.2

8

2

6

5

.2

2

2

6

5

.0

7

2

6

5

.1

1

2

6

5

.2

2

2

6

5

.8

2

2

6

5

.9

1

267.1

4

266.95

267.90

267.69

266.94

266.97

267.02

267.01

267.63

267.58

267.34

268.09

267.97

267.65

267.19

2

6

6

.

1

9

2

6

6

.

1

9

266.1

0

265.39

265.18

264.5

9

264.4

9

267.27

267.46

267.56

267.65

268.00

267.95

267.9

3

2

6

8

.

4

2

268.43

267.54

267.58

267.99

268.18

268.75

2

6

8

.

8

7

2

6

6

.

4

3

2

6

7

.0

2

267.56

2

6

8

.

5

3

2

6

8

.

4

4

2

6

8

.

4

6

2

6

8

.

4

6

267.8

3

2

6

8

.4

0

2

6

8

.0

9

268.2

2

268.4

5

268.4

4

268.46

268.45

268.4

6

2

6

8

.9

1

2

6

8

.9

3

268.87

2

6

8

.8

8268.89

268.9

3

268.9

2

2

6

8

.

9

1

269.17

269.27

269.30

269.23

269.03

268.84

2

6

8

.7

1

2

6

8

.6

0

2

6

9

.0

1

2

6

8

.5

5

2

6

8

.7

3

2

6

8

.5

9

2

6

8

.7

5

2

6

8

.3

6

2

6

7

.7

1

2

6

7

.7

5

2

6

7

.5

4

2

6

7

.5

8

2

6

7

.4

4

2

6

7

.4

6

2

6

7

.4

6

2

6

7

.4

2

267.90

2

6

7

.4

0

267.4

6

267.4

7

268.7

0

268.8

3

268.6

0

268.7

4

268.7

1

2

6

8

.

2

5

2

6

8

.

2

4

2

6

8

.

4

4

2

6

8

.

1

0

2

6

7

.

7

7

2

6

7

.

6

3

2

6

7

.

5

3

2

6

7

.

3

9

267.67

2

6

7

.

2

3

2

6

7

.

1

0

2

6

6

.

9

1

2

6

6

.

7

2

267.22

267.10

266.98

266.81

266.84

266.95

267.10 267.31

267.34

267.34

267.46

267.43

267.44

267.43

267.39

267.35

267.33

267.22

2

6

6

.

4

6

267.27

2

6

6

.

9

8

267.47

267.65

267.7

4

267.7

3

2

6

7

.

9

5

266.0

4

2

6

5

.9

9

268.2

9

2

6

8

.

3

42

6

6

.

5

8

267.44

2

6

8

.

3

4

2

6

8

.

3

2

2

6

8

.

3

1

2

6

8

.

3

4

2

6

8

.

3

3

2

6

8

.

3

3

2

6

8

.

3

2

2

6

7

.9

6

2

6

7

.8

5

267.88

2

6

7

.

8

7

267.96

2

6

7

.9

2

2

6

7

.

4

7

2

6

7

.

4

4

267.71

267.56

2

6

7

.7

7

265.36

2

6

5

.3

8

2

6

5

.

5

4

2

6

6

.

6

8

2

6

6

.

7

6

2

6

5

.

9

2

2

6

5

.

9

2

265.97

266.05

267.7

3

267.4

2

266.8

2

266.8

6

266.5

0

266.2

7

265.4

7

265.2

2

265.0

3

264.6

5

265.84

265.15

265.28

265.25

265.43

265.27

265.38

265.25

264.99

265.18

265.00

264.98

264.91

266.19

266.65

266.49

266.89

266.56

266.65

267.01

267.05

2

6

9

.2

9

2

6

9

.3

5

269.4

0

2

6

9

.

4

0

268.68

268.25

268.36

268.25

268.55

268.98

269.05269.03

2

6

8

.

2

4

2

6

8

.

3

5

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1

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267.80

267.57

268.02

267.80

267.13

267.05

XS7

XS8

XS9

XS10a

XS10b

XS11

XS12

XS13

Unable to survey

centre of weir

and downstream pool

Do not scale this drawing

Status

Client

Project

Title

Drawing No. Revision

File path:

Scale Date

ApprovedCheckedDrawn

Rev Date InitialsAmendment

Craighall BusinessPark, Eagle Street,

Glasgow, G4 9XATel: 0141 341 5040Fax: 0141 341 5045

A1

Notes

k:\368420\drgs\cad\working

Don District Salmon Fishery Board

Newe Weir Removal

Topographical survey of weir location

DRAFT368420-SK-001 A

1:500 15/05/2017

DW KMD KMD

newe weir, river don weir removal technical · pdf filenewe weir, river don weir removal...

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